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Openreach modem (ONT) explained: Ports and models available

If you are a fibre customer, it’s likely you’ll have an Openreach modem (or ONT) installed. This white box connects to a fibre-optic cable that runs to your house and enables you to access our FTTP fibre network for broadband and voice.

There are several lights on the ONT, when these lights change colour or flash, it means something is happening.

What do the lights on the Openreach fibre modem mean? >

Openreach modem ports

  • Optical: This hosts the fibre optic cable that comes from the exchange to your house.
  • PORT 1: Here you plug in an Ethernet cable that runs to your BT Hub. Some modems have multiple ports.
  • TEL 1: Digital voice customers can use this to plug in a telephone.
  • BBU: This port attaches to the battery back-up unit, if there is one.  
  • DC: Depending on your modem, this connects to the power supply or the BBU unit

Types of Openreach modem

There are five different types of Openreach modem. There are slight variations in the way they look including the lights, but they all do the same job.

Huawei 1-port modem

This modem comes with a back-up battery Pack (BBU) in a white box, which enables your phone to continue to work after a power cut. The engineer will install on your wall. The flap protects the cables and the front door opens so you can reach the ports. 

Huawei 4-port modem

This modem has four ports, you will probably only use ‘PORT 1’ to connect your Smart Hub.

Huawei 4-port Openreach modem

ECI modem

ECI fibre modem

ECI C-Series modem

ECI C-series modem

Nokia modem

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